Imaging systems may be arranged to output an image. They may comprise printing or display systems, wherein an output is either a printed or displayed image. In these cases, color data for the image may be represented in a first color space, such as a Red, Green, Blue (RGB) color space. An imaging system may have a limited number of output channels such as colorants or light-emitting elements. As such, it may be necessary to map the color data to a second color space that is used to produce the output. Area coverage representations, such as Neugebauer Primary area coverages for example, may be used in this second color space. There may be multiple area coverage representations that can be mapped to a particular color in the first color space. These are referred to as metamer sets. To determine a metamer set, due to the high dimensionality of the second color space, a polyhedral search may be used.